<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Document</title>
    <style>
        /* 包含全部子孙后代 */
    .bw1 a{
        color: green;
    }

    .bw2 ul li{
        color: red;
    }
    </style>
</head>
<body>
    <div class="bw1">
        <a href="#">后代选择器11</a>
        <a href="#">后代选择器11</a>
    </div>
    <a href="#">后代选择器22</a>
    <a href="#">后代选择器22</a>

    <div class="bw2">
        <ul>
            <li>111</li>
            <li>111</li>
        </ul>
    </div>
    <ul>
        <li>222</li>
        <li>222</li>
    </ul>
</body>
</html>